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CESIS Electronic Working Paper Series Paper No. 332 Which Types of Relatedness Matter in Regional Growth? - industry, occupation and education Sofia Wixe Martin Andersson November, 2013 The Royal Institute of technology Centre of Excellence for Science and Innovation Studies (CESIS) http://www.cesis.se

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Page 1: Which Types of Relatedness Matter in Regional Growth ... · Which Types of Relatedness Matter in Regional Growth? - industry, occupation and education Sofia WixeƟ and Martin AnderssonØ

CESIS Electronic Working Paper Series

Paper No. 332

Which Types of Relatedness Matter in Regional Growth?

- industry, occupation and education

Sofia Wixe Martin Andersson

November, 2013

The Royal Institute of technology Centre of Excellence for Science and Innovation Studies (CESIS)

http://www.cesis.se

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2

Which Types of Relatedness Matter in Regional Growth?

- industry, occupation and education

Sofia WixeƟ and Martin AnderssonØ

Abstract This paper provides a conceptual discussion of relatedness, which suggests a focus on

individuals as a complement to firms and industries. The empirical relevance of the main

arguments are tested by estimating the effects of related and unrelated variety in

education and occupation among employees, as well as in industries, on regional growth.

We show that for regional productivity growth, occupational and educational related

variety matter over and above industry relatedness. This supports the conceptual

discussion put forward. The potential of productive interactions between employees in a

region is greater when there is related variety in their ‘knowledge base’. We also find that

related variety in industries is positive for employment growth but negative for

productivity growth.

Keywords: Relatedness, variety, occupation, education, regional growth.

JEL: R12, R23, J24

____________________________

Ɵ Corresponding author. Centre for Entrepreneurship and Spatial Economics (CEnSE), Jönköping International

Business School, P.O.Box 1026, 551 11 Jönköping, Sweden. E-mail: [email protected].

Ø Centre for Innovation, Research and Competence in the Learning Economy (CIRCLE), Lund University.

Acknowledgements: Sofia Wixe gratefully acknowledges financial support from the Swedish Research Council

Formas (Grant 2009-1192), the European Union/European Regional Development Fund (Grant 162 888), the

Regional Development Council of Jönköping County and the County Administrative Board in Jönköping. Martin

Andersson acknowledges financial support from FORMAS (Dnr 2011-80), as well as the Swedish Research

Council (Linnaeus Grant No. 349200680) and the Swedish Governmental Agency for Innovation Systems,

VINNOVA (Grant agreement 2010-07370).

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1. INTRODUCTION

Within the fields of urban economics, economic geography and regional science, there has been a

long-standing debate on the effects of agglomeration economies on growth. Much work in this strand

of research focuses on the question whether industry specialization or diversity is more important in

promoting growth (Boschma and Iammarino 2009). Glaeser et al. (1992) and Henderson et al. (1995)

led the way and many researchers have followed in similar tracks. However, the point of departure for

the present paper is Frenken et al. (2005; 2007) who took the question about regional diversity, or

variety, one step further. Following Noteboom (2000), they argue that for knowledge spillovers to

enhance growth, there needs to be some sort of cognitive proximity or complementarity between

firms. A distinction was thus made between related and unrelated variety where related variety is

defined as within-industry diversity and unrelated variety as between-industry diversity. Frenken et al.

(2007) is in this regard a seminal study as it is one of the first to provide systematic evidence of that it

is not variety in general, but variety in related industries that promotes regional employment growth.

This finding has been confirmed in several studies using data from different countries and time periods

(Boschma and Iammarino 2009; Boschma et al. 2012; Hartog et al. 2012).

A conceptual issue in relation to this concerns defining relatedness. In the present paper we address

this question and argue that measuring relatedness is not straightforward since relatedness may have

many dimensions. We put forth arguments and provide empirical support for that relatedness framed

at the level of individuals, e.g. in terms of educational background and occupation, is at least as

important as relatedness in terms of industries. Indeed, the downsides of applying standard industrial

classifications to approximate relatedness have been discussed critically in a number of papers, such as

Ejermo (2005), Bishop and Gripaios (2010), Brachert et al. (2011), Desrochers and Leppälä (2011)

and Boschma et al. (2012).

In contemporary economies cities or regions tend to specialize in functions rather than in industries.

Certain occupations are found in specific cities, due to headquarters and business services being

localized in larger cities while actual production takes place in more rural areas (Duranton and Puga

2005). Larger cities are thus specialized in knowledge-intensive occupations over a wide range of

industries, which implies that variety in occupations have the potential to be at least as important for

growth as variety in industries. Since certain occupations are found in different cities it is also likely

that certain education types are found in those cities. Education and occupation are linked together,

more so than education and industry. In many cases, higher education is usually undertaken to work

within a certain range of occupations, not to work in a specific industry. The relationship between

education and occupation is still not clear-cut, with the consequence that education and occupation are

measures of quite different things. Education measures the formal, theoretical background of

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employees while occupation is a measure of what the employees actually do in their daily work.

Indeed, occupation is commonly used as a proxy for the skills and abilities of the employees beyond

their formal education (cf. Autor et al. (2003) and Bacolod et al. (2009)). However, as Frenken et al.

(2007), most research still focus on the effect of industrial specialization (or variety) on growth.

Duranton and Puga (2004) distinguish between three types of mechanisms behind agglomeration

economies; sharing of e.g. fixed costs and risk, matching on the labor market, and learning due to

knowledge spillovers and human capital accumulation. They also emphasize that heterogeneity of

workers and firms is the foundation for these effects to materialize. From this perspective regional

variety has the potential to give rise to agglomeration economies, which may stimulate innovation and

growth. However, in a strict sense, both the matching and learning argument emphasize individuals

rather than firms. Knowledge and information may not spill over between firms per se, but rather

between employees, who channel that knowledge, in different firms. Cohen and Levinthal (1990)

discuss this in terms of firms’ absorptive capacity. There are thus arguments in favor of framing issues

of cognitive proximity and relatedness in terms of individuals. On these grounds, relatedness in terms

of employee education and occupation are emphasized in the present paper. Previous research have

indeed expanded the measures of related variety beyond industrial classifications (cf. Boschma et al.

(2012)), but the main focus is still on industry- and product level, not the specific characteristics of the

employees.

To test the empirical relevance of these ideas, we make use of data on Swedish regions and estimate

the respective influence of the different dimensions of relatedness on regional growth over a five-year

period (2002-2007). We follow the original work by Frenken et al. (2007) and compute related and

unrelated variety in terms of industries, but also include additional measures of related and unrelated

variety in terms of occupation and education of the workers in each region. The inclusion of the two

individual-based measures of occupational and educational variety constitutes the main novelty in the

empirical analysis. We further include variables reflecting general agglomeration economies as well as

a selection of control variables. The model is estimated for regions as a whole as well as for

manufacturing and service industries, respectively. This is motivated by the results from Bishop and

Gripaios (2010), which show different effects of unrelated and related variety on employment growth

in different industries.

The results show that the effects of related and unrelated variety differ considerably, both across the

different dimensions of relatedness and across sectors. This confirms the importance of expanding the

concept of relatedness beyond the industrial dimension. We find that occupational and educational

related variety matter over and above industry relatedness in explaining regional productivity growth.

Relatedness in terms of sharing a common educational background appears to be particularly

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correlated with productivity growth in the manufacturing sector. These result may be appreciated as a

reflection of that relatedness in terms of education and occupation stimulate matching processes on

local labor markets as well as local knowledge spillovers, i.e. two established micro-foundations for

agglomeration economies. Hence, regions with a variety of jobs associated with related educations

and/or related tasks may facilitate matching externalities on the labor market as well as inter-firm

knowledge transfers through employee mobility. We also confirm the results of Frenken et al. (2007),

namely that related industry variety is negatively associated with productivity growth but positively

associated with employment growth.

The rest of the paper is organized as follows. Section 2 provides further background and motivation

for the paper, including related empirical research. Section 3 gives an overview of the data and the

variables used in the empirical application, while section 4 presents the empirical results, which give

evidence to what has been argued in the previous parts of the paper. Finally, section 5 concludes.

2. BACKGROUND AND MOTIVATION

2.1 Relatedness based on firms or individuals

Recent contributions in economic geography and regional science hold that local variety of related

industries is crucial in fostering regional growth (Frenken et al. 2007). The main argument in this

literature is that effective knowledge transfers and spillovers between activities in a region require that

they are cognitively related, though some cognitive distance is still needed to limit overlaps and to

alleviate issues of lock-in (Boschma 2005). Variety in related activities is thus maintained to stimulate

productive interactions and cross-fertilizations within a region, because it ensures cognitive proximity

while maintaining some distance (through variety). This line of reasoning builds on Noteboom’s

(2000) conjecture of “optimal cognitive distance”. Noteboom states that “information is useless if it is

not new, but it is also useless if it is so new that it cannot be understood” (Noteboom 2000, p.153).

While the general line of argument is clear, i.e. that there is a tradeoff between cognitive distance for

the sake of novelty and cognitive proximity for the sake of mutual understanding and absorptive

capacity, the question is what makes relatedness in a regional context, i.e. what characteristics of a

local economy bodes for cognitive proximity? This is an issue that is not only of academic interest, but

is also important from a policy perspective. Any discussion of policy initiatives based on the idea of

relatedness will for example bring with it a concern regarding what relatedness means and how it can

be defined and assessed.1 The idea of relatedness has had a quite large impact on both the research and

1For example, Frenken et al. (2007, p.696) conclude: “Regional policies based on supporting related variety

reduce the risk of selecting wrong activities because one takes existing regional competences as building blocks

to broaden the economic base of the region.” Picking the ‘right’ activity obviously necessitates knowledge of

what makes relatedness.

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the policy community, and is also embedded in the European Union current regional innovation policy

concept of smart specialization (cf. McCann and Ortega-Argilés (2013).

The majority of existing analyses puts firms at the center stage and frame discussions about

relatedness in an inter-firm context. A main hypothesis is that relatedness between firms hinges on

their industry affiliations, such that firms operating in similar industries have shared competences and

thus cognitive proximity at the organizational level (cf. Boschma and Martin (2010)). In view of this,

empirical applications typically infer relatedness from pre-determined industry or product

classification schemes (Frenken et al. 2007; Boschma et al. 2012). Put simply, the potential for

productive inter-firm knowledge transfers and spillovers is assumed to be higher when firms operate in

industries that are closer to each other in the standard industrial classification system or produce

similar products (Van Oort 2013).

Following Desrochers and Leppälä (2011), it may still be argued that the firm- and industry-level

focus in the literature on relatedness downplays that much of the learning and spillovers in regions

occur at the level of individuals. That is, a strong case can be made that knowledge spillovers between

firms in a region are to a large extent attributed to spillovers between their employees. Knowledge

may flow between firms for example because their employees learn from others in their local

environment, or because employees move between them, which induces cross-fertilizations. For

instance, the theoretical as well as empirical literature on human capital externalities and local non-

market interactions (Lucas Jr. 1988; Rauch 1993; Glaeser and Scheinkman 2003) explicitly put social

interactions between individuals at center stage. Likewise, a large literature show that movements of

individuals between firms is a key source of spillovers and transfers of knowledge and information

(Almeida and Kogut 1999; Maskell and Malmberg 1999; Power and Lundmark 2004). It follows that

the central ‘agents’ in the context of spillovers and knowledge transfers are not firms per se, but

individuals. While this may seem like a trivial statement, the key point is that an emphasis on

individuals have implications for the question of the dimension of relatedness that stimulate

productive knowledge spillovers.

Accepting individuals as the main agents for knowledge spillovers suggest arguments in favor of

framing issues of cognitive proximity in terms of individual skills, experiences and knowledge. The

industry dimension can in this perspective be problematic on the grounds that experiences and

knowledge bases of individual employees have more to do with their occupational and educational

background. Many firms have for example a sharp division of labor where individual employees work

with a narrowly defined and specialized task, often matched with their university degree. Therefore,

workers’ experiences and on-the-job learning may to a large extent be considered as occupation- and

education-dependent, rather than industry-dependent. For example; a software engineer developing

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steering-systems for industrial robots at ABB Corporation may have cognitive proximity with a

software engineer at an engineering service company, albeit the two industries are radically different

as judged by their industrial classifications. Inter-firm job switching of personnel between such firms

may also be large for the same reason. In many cases, employers also value occupational- and task-

specific experiences rather than specific industry experience when hiring new personnel.

Furthermore, there is ample evidence that industries have very different occupational and educational

composition in different regions, a phenomena dubbed ‘functional specialization’ by Duranton and

Puga (2005). This means that the experiences, and hence the position in the ‘cognitive space’, of

workers in one and the same industry may be quite different across locations. This is a potentially

important aspect that the traditional industry- and product-based measures of relatedness cannot

capture. Occupational and educational relatedness should thus better reflect cognitive proximity at an

individual level, because they depart from what employees actually do in their work, i.e. their

immediate learning and experience context, as well as their knowledge base in terms of formal

education. Our basic hypothesis is that this type of individual-level relatedness is at least as important

as industry relatedness in providing a breeding ground for productive local knowledge spillovers and

cross-fertilizations, and thus in influencing regional growth.

Similar ideas are raised by Neffke and Henning (2013) with the concept of skill relatedness. Especially

high-skilled individuals are likely to change jobs within industries that value the same types of skills.

This implies that relatedness between industries can be determined based on cross-industry labor

flows. Neffke and Henning (2013) use this in order to explain the diversification strategies of firms,

which determine regional industrial diversification. The results show that firms are more likely to

diversify into industries with which there is skill relatedness than with industries without such

relatedness or with relatedness in terms of standard industrial classifications.2 While we also

emphasize the individual-level, our contribution is different in that we study relatedness in terms of the

educational and occupational profile of regions and test their role in explaining regional growth

alongside the industry relatedness.

2 Since this characterization of relatedness is derived from actual flows of labor it is sensitive to changes in labor

flows between years and differences in labor flows between regions. In addition, if employees in certain

occupations are more likely to switch jobs than employees in other occupations there is a risk that relatedness

between industries is not properly captured by labor flows. When instead focusing on the educational

background and current occupation among employees, no matter the industry boundaries, the definition of

relatedness is time-invariant and insensitive to changes on the market.

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2.2 Related empirical research

There are numerous empirical studies on the effects of agglomeration economies on growth. Most of

these use a broad measure of industry diversity over the economy or region as a whole, that is Jacobs

externalities are measured as unrelated rather than related variety (cf. Glaeser et al. (1992), Henderson

et al. (1995), Duranton and Puga (2000)). However, some studies acknowledge the complexity of

diversity, most notably the one by Frenken et al. (2007), who analyze the effects of unrelated and

related industry variety on growth in employment, unemployment and productivity in Dutch regions.

The results of the study show that, as expected, related variety enhances employment growth while

unrelated variety is negatively related to unemployment growth. The productivity growth of a region is

negatively associated with related variety.

Bishop and Gripaios (2010) conduct a similar study of British regions when analyzing the effects of

unrelated and related variety on employment growth in different industries. The results show that the

effects of unrelated and related variety differ across the examined industries, of which nearly 50 per

cent benefit from either one of the two forms of variety. Unrelated variety is affecting employment

growth in a larger set of industries than related variety. Regarding regional employment growth in

Germany Brachert et al. (2011) find no effects from neither unrelated nor related variety. However,

related variety in combination with functional specialization, in terms of more “white collar” workers,

positively influences employment growth. In addition, unrelated variety among “white collar” workers

and “blue collar” workers, but not R&D workers, is found to enhance growth. When analyzing growth

in Spanish provinces Boschma et al. (2012) find that related variety has a positive effect on value

added growth while unrelated variety has no growth effect. The results also show that the positive

effect is stronger when using indicators for related variety not only based on product classifications.

Boschma et al. (2012) construct one measure based on Porter’s (2003) cluster classification of

industries and one based on export data. Hartog et al. (2012) analyze the effects of related variety on

employment growth in Finnish regions. The results show that related variety in general has no effect

but that related variety in high-tech industries positively influences employment growth. No growth

effect is found from unrelated variety.

The concept of related and unrelated variety has been quite commonly applied in relation to

international trade. Saviotti and Frenken (2008) analyze the relationship between export variety and

economic development in 20 OECD countries. An increase in the growth in related export variety is

found to promote growth in GDP per capita, while an increase in the growth in unrelated export

variety has a negative effect. However, past growth in unrelated export variety positively influences

economic growth. Also Boschma and Iammarino (2009) consider export variety, when analyzing the

effects on regional economic growth in Italy. Related, but not unrelated, export variety is found to

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significantly enhance value-added growth. In addition, as mentioned above, one of Boschma et al.’s

(2012) alternative measures of related variety is based on export data.

3. DATA AND VARIABLES

The regions referred to in the empirical part of the paper are the 290 municipalities in Sweden.3 These

are the smallest administrative units in Sweden. All variables described below are measured at the

municipal level.

3.1 Dependent variables

We employ two different dependent variables; (i) employment growth and (ii) productivity growth.

Frenken et al. (2007) find that related variety has a negative influence on productivity growth but a

positive influence on employment growth. They maintain that this is consistent with the idea that

employment growth better reflect radical innovation as such innovations are assumed to lead to the

creation of new markets and employment. Productivity growth is instead associated with process

innovations and growing capital intensity in the later stages of the product life cycle (cf. Van Oort

(2013)). That related variety spurs employment growth and not productivity growth is thus taken as

evidence that related variety has more to do with knowledge spillovers and (radical) innovation. While

this argument is conceptually appealing, it can also be argued that productivity is after all the main

determinant for long-run growth (Easterly and Levine 2002). A vast literature also document the

fundamental role played by innovation and new technology in stimulating productivity (Lööf and

Heshmati 2002; Hall and Mairesse 2006).4 Hence, there are also arguments in favor of that the

productivity growth of a region is related to innovation. A defining characteristic of urban regions, that

typically are more diversified, is indeed also higher productivity levels, not least in Sweden (cf.

Andersson and Lööf (2011)).

We measure productivity growth as the ratio between average labor productivity in 2007 and 2002.

Employment growth is measured as the ratio between total number of employed for the same set of

years. However, a region might exhibit a higher growth rate simply because it has a relatively large

share of one or more fast growing industries. As robustness test, we therefore also apply a shift-share

procedure for both productivity growth and employment growth. This implies that the growth in each

2-digit industry is weighted by the industry’s national share of production in the case of productivity

3 Gotland is excluded due to having no neighbors. Hence, the number of observations in the estimations is 289.

4In fact, it has also been argued that productivity growth may be used as an innovation indicator (Hall 2011).

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growth and by the industry’s share of employment in the case of employment growth. This imposes

the same industrial structure in all regions and produces industry-adjusted growth rates.5

Productivity growth and employment growth are constructed for the whole private sector of the

regional economy, as well as for the manufacturing sector and the service sector separately. The

development in the public sector is more difficult to relate to spatial characteristics since it is largely

dependent on political decisions. Also agriculture, fishery and mining are excluded since these

industries are more or less spatially bounded due to immobile resources. This leaves the industries in

standard industrial classification (SIC) codes 15 to 74, of which 15 to 45 belong to the manufacturing

sector6 while 50 to 74 are service industries.

3.2 Independent variables

All independent variables are measured for the year 2002, unless otherwise specified. The six

independent variables of main interest are; related variety in industries, education and occupation, and

unrelated variety in industries, education and occupation. The entropy (or the Shannon index)

approach is commonly applied for measuring variety, see for example Jacquemin and Berry (1979),

Attaran (1986) and Frenken et al. (2007). The entropy measure has desirable properties in that it takes

the relative abundance of groups into account, and not only the absolute presence of them. The entropy

for unrelated variety measures between diversity while the entropy for related variety measures within

diversity, in e.g. industries. All entropies are calculated using employment in each group. The data is

limited to employed individuals between 20 and 64 years of age with a positive income.

For industries the 2-digit and the 5-digit SIC codes are used where each 5-digit industry belongs to a

specific 2-digit industry7. Following Attaran (1986), let Sg denote the 2-digit sets where g = 1,…, G. Eg

denotes the share of employees working in the 2-digit industry g, where Eg is measured as the share of

total regional employment. Furthermore, let Eig denote the share of employees working in the 5-digit

industry i, where i = 1,…, I, where Eig is measured as the share of employment in the respective 2-digit

industry g.

Unrelated variety in industries measures the distribution of employees between 2-digit industries.

Using the entropy approach, unrelated variety (UV) is calculated as follows:

5 See Table A1 in Van Stel and Storey (2004) for an illustration of the shift-share procedure.

6 Including construction.

7 An example: Industry 15111 and 15120 are sub industries to industry 15.

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(1)

The range of UV is from 0 to where zero variety is reached when all employees are working in

the same 2-digit industry, that is when one Eg = 1 while the rest are zero. Maximum variety, i.e. ,

is reached when there is an equal distribution of employees over all 2-digit industries, that is all Eg are

identical. (Attaran 1986)

In the same manner, the distribution of employees between 5-digit industries within each 2-digit

industry is calculated as follows:

(2)

The interpretation of Equation 2 is the same as for Equation 1 with the difference that variety is

measured within each 2-digit industry rather than between the 2-digit industries. Hence, there is zero

within variety when all employees in the 2-digit industry g are working in the same 5-digit industry i,

where . Accordingly, maximum variety for industry g, , is achieved when there is an equal

distribution of employees over all 5-digit industries i, where .

The information about the degree of within variety for each 2-digit industry g, i.e. Hg, is weighted by

the relative size of industry g. Summing over all g gives the entropy measure for related variety in

industries (RV), regarding the region as a whole. These two steps are formally shown by Equation 3.

(3)

Increases in the values obtained by Equation 1 and 3 imply increases in unrelated and related variety,

respectively.

Unrelated and related variety for the educational and the occupational dimension are calculated as

above, with the difference that the educational and the occupational codes are used instead of the SIC

codes. When constructing the measures for educational variety we use a combination of education

length and specialization. Employees are first categorized as either having three or more years of

higher education or not. After this categorization education specialization is used at the 2- and 4-digit

levels. This implies that employees belonging to the same 2-digit educational code and have three or

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more years of higher education are seen as related. Education focus is divided in 26 different 2-digit

levels (see Table A1), the maximum possible G for the educational dimension is hence 52. Regarding

the occupational dimension occupational codes at the 1- and 3-digit levels are used instead of the

educational codes. Occupations are divided in 12 different 1-digit levels (see Table A2), which implies

that the maximum possible G for the occupational dimension is 12. Figures A1-3 in Appendix 2

provide maps of Sweden, showing the distribution of related and unrelated variety over municipalities

in 2002. These can also be compared to Figure A4, which presents the population density in Sweden.

Besides unrelated and related variety, we also control for the presence of general urbanization

economies measured as population density, Porter externalities or competition measured as firms per

employee, and localization economies or specialization. There are various approaches to measure

specialization, both in absolute and relative terms. In the context of localization economies absolute

specialization is relevant since it is the absolute agglomeration of employees belonging to the same

industry that has the potential to give rise to knowledge spillovers. Since an increase in unrelated

variety in industries implies a decrease in absolute industrial specialization the entropy for unrelated

variety in industries is used also as a proxy for industrial specialization (as in Aiginger and Davies

(2004)). The entropy measure is not as commonly applied to measure specialization as for example the

Herfindahl index but the two are strongly correlated (Palan 2010).

Considering previous studies of regional productivity growth, the capital-labor ratio is introduced as a

control variable when estimating growth in productivity. Size effects are controlled for by introducing

absolute values for 2002. All independent variables, besides population density, are calculated for

industry 15-74 as a whole but also for the manufacturing sector and the service sector separately.

Appendix 3 provides tables with descriptive statistics for the variables regarding the private sector as a

whole, as well as for the manufacturing sector and the service sector separately. To reduce

heteroscedasticity, as well as to facilitate the interpretation of the coefficients to be estimated, all

variables are log transformed. Appendix 4 presents correlation matrices over all independent variables

for the total private sector, the manufacturing sector and the service sector. Regarding the service

sector, there is strong correlation between related and unrelated variety in industries. To avoid

problems with multicollinearity, unrelated variety in industries is excluded when estimating models

for the service sector. In addition, the initial employment level is excluded due to problems with

multicollinearity. Besides this correlation between explanatory variables is not an issue, which is

confirmed when running post diagnostic tests for multicollinearity.

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4. MODEL AND EMPIRICAL ESTIMATIONS

The model used as a point of departure for estimations is given by equation 5:

+ (5)

in which Growthr refers to growth in either productivity or employment in municipality r. RVr is a row

vector of related variety in industries, education and occupation, respectively and UVr is the

corresponding vector for unrelated variety. Controlr contains the set of control variables, which

depends on the Growth variable in question. εr is the error term, which by assumption is uncorrelated

with the individual variables. The parameters are estimated by ordinary least squares (OLS), with

robust standard errors in the cases where heteroscedasticity is detected. However, since the data is

based on geographic units there is a potential issue of spatial dependence, municipalities might be

correlated simply due to geographic proximity. This is tested by Moran’s I on the residuals from the

OLS regressions. In the presence of spatial autocorrelation the coefficients from the OLS regressions

are inefficient why spatial error and spatial lag models are estimated by maximum likelihood (ML).

The use of spatial econometrics to deal with spatial dependence is debated, mostly due to issues of

identification (Gibbons and Overman 2012). Hence, the spatial models are estimated mainly as

robustness checks for the OLS models and will not be analyzed in detail. More information about the

spatial models as well as the results from these estimations are presented in Appendix 5.

Table 1 presents the results for productivity growth and employment growth for the private sector as a

whole, including both unadjusted and industry-adjusted growth rates. Spatial autocorrelation is present

in the model for industry-adjusted employment growth since Moran’s I is statistically significant for

this model.

The results show that the relationships between the different dimensions of related and unrelated

variety and growth differ considerably, which gives evidence to the importance of distinguishing

between various forms of variety. As in Frenken et al. (2007), related variety in industries is positive

for employment growth, both unadjusted and adjusted, while it is negative for unadjusted productivity

growth. The results for related variety in education are consistent when it comes to growth in

productivity. Higher related variety in education is associated with higher unadjusted as well as

adjusted productivity growth.8 The estimated relationship is significantly larger than the relationship

between related variety in industries and employment growth.

8 The same patterns are found when conducting the analysis at the level of functional regions. However, due to

few observations at this level as well as recent research showing that agglomeration economies, in particular

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Table 1. Estimated coefficients for productivity growth and employment growth in the total private

sector, standard errors in brackets.

Variables 1a

Productivity

1b

Productivity

Adjusted

2a

Employment

2b

Employment

Adjusted

RV Industry -0.130**

(0.054)

0.026

(0.075)

0.097***

(0.029)

0.162***

(0.051)

UV Industry 0.097

(0.115)

0.497***

(0.181)

-0.042

(0.082)

0.041

(0.143)

RV Education 0.562***

(0.129)

0.515***

(0.191)

0.018

(0.097)

-0.036

(0.219)

UV Education 0.227

(0.156)

0.308

(0.284)

0.023

(0.096)

-0.320*

(0.187)

RV Occupation 0.097

(0.178)

0.108

(0.199)

-0.083

(0.076)

0.032

(0.142)

UV Occupation -0.468**

(0.218)

-0.574

(0.413)

0.068

(0.150)

0.371

(0.305)

Competition 0.020

(0.030)

-0.047

(0.058)

0.049**

(0.022)

-0.097*

(0.050)

Population density 0.002

(0.008)

0.027***

(0.009)

-0.002

(0.004)

0.024***

(0.006)

Capital-labor growth 0.149***

(0.031)

0.046

(0.043)

Productivity 2002 -0.223***

(0.056)

-0.119

(0.088)

Constant 1.44***

(0.356)

0.052

(0.561)

0.143

(0.114)

-0.350

(0.243)

F-value 11.7*** 11.9*** 7.43*** 9.85***

R2 0.286 0.178 0.175 0.227

Moran’s I p-value 0.374 0.446 0.398 0.045

Observations 289 289 289 289

Notes: *** p<0.01, ** p<0.05, * p<0.1. Robust standard errors in Model 1a, 1b and 2b.

Hence, the results for related variety in industries for the Swedish economy is in line with Frenken et

al.’s (2007) findings for the Netherlands. The higher employment growth in regions with greater

related variety is consistent with the argument that related variety in sectors spur knowledge spillovers

that in turn influence employment growth. The finding that related but not unrelated variety in

education is positively associated with unadjusted and adjusted productivity growth may be interpreted

as a reflection of that there needs to be complementarity in educational background among employees

for knowledge spillovers to be productive. A mechanical engineer may learn more from a materials

engineer than a sales representative, no matter their industry. One reason for this could be that they

share a common knowledge base. We find no clear association between related and unrelated variety

in occupation and the two measures of growth.

concerning knowledge spillovers, attenuate sharply with distance (cf. Baldwin et al. (2008) and Andersson et al.

(2012)), municipalities are chosen as the level of analysis.

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Tables 2 and 3 present the results for growth in productivity and growth in employment, when the

private sector is split into manufacturing and services. Regarding productivity, we find spatial

autocorrelation in the model for adjusted growth in the manufacturing sector and unadjusted growth in

the service sector. For employment growth spatial autocorrelation is detected for the service sector

only, in both unadjusted and adjusted growth rates.

Table 2. Estimated coefficients for productivity growth in the manufacturing sector and the service

sector, standard errors in brackets.

Variables 3a

Manufacturing

3b

Manufacturing

Adjusted

4a

Services

4b

Services

Adjusted

RV Industry -0.106***

(0.036)

0.087

(0.060)

-0.133***

(0.046)

-0.129*

(0.073)

UV Industry 0.043

(0.062)

0.149

(0.102)

RV Education 0.659***

(0.150)

1.36***

(0.247)

-0.045

(0.116)

0.091

(0.167)

UV Education -0.102

(0.187)

0.168

(0.308)

0.731***

(0.261)

0.820*

(0.434)

RV Occupation 0.026

(0.077)

0.083

(0.126)

0.260***

(0.090)

0.425*

(0.226)

UV Occupation -0.186

(0.138)

0.023

(0.228)

-0.382

(0.236)

-0.492

(0.687)

Competition 0.052*

(0.028)

0.062

(0.046)

-0.052

(0.035)

0.044

(0.094)

Population density -0.006

(0.007)

0.034***

(0.011)

0.011*

(0.006)

0.017*

(0.010)

Capital labor growth 0.154***

(0.022)

-0.008

(0.036)

0.064**

(0.028)

0.087**

(0.044)

Productivity 2002 -0.211***

(0.041)

-0.132**

(0.067)

-0.492***

(0.100)

-0.300

(0.221)

Constant 1.54***

(0.269)

0.207

(0.444)

2.74***

(0.546)

1.61

(1.22)

F-value 12.4*** 15.1*** 8.65*** 2.26**

R2 0.308 0.352 0.253 0.085

Moran’s I p-value 0.143 0.001 0.028 0.346

Spatial coefficient

Observations 289 289 289 289

Notes: *** p<0.01, ** p<0.05, * p<0.1. Robust standard errors in Model 4a and 4b.

The results for the manufacturing sector and the service sector in Tables 2 and 3 show both similarities

and differences from the private sector as a whole, which points to the importance of distinguishing

between different parts of the economy. The negative productivity effect from related variety in

industries is present in the service sector for both unadjusted and adjusted growth rates. In addition,

this effect is found for unadjusted growth in the manufacturing sector. Hence, the result that related

variety in industries negatively associated with productivity growth is robust. The positive

employment effect from this variable is significant only for unadjusted growth in the service sector.

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Table 3. Estimated coefficients for employment growth in the manufacturing sector and the service

sector, standard errors in brackets.

Variables 5a

Manufacturing

5b

Manufacturing

Adjusted

6a

Services

6b

Services

Adjusted

RV Industry -0.019

(0.029)

-0.019

(0.068)

0.076***

(0.029)

0.048

(0.043)

UV Industry -0.146***

(0.050)

0.042

(0.141)

RV Education 0.170

(0.118)

0.580**

(0.240)

0.130

(0.105)

0.155

(0.202)

UV Education -0.140

(0.149)

-0.446

(0.305)

-0.264*

(0.154)

-0.165

(0.204)

RV Occupation 0.109*

(0.061)

0.377***

(0.146)

0.009

(0.093)

0.109

(0.142)

UV Occupation 0.008

(0.110)

0.315

(0.232)

-0.447*

(0.235)

-0.378

(0.333)

Competition 0.068***

(0.022)

-0.003

(0.043)

0.089***

(0.032)

0.025

(0.066)

Population density -0.016***

(0.005)

0.040***

(0.011)

0.013**

(0.005)

0.015**

(0.007)

Constant 0.261

(0.106)

-0.471**

(0.215)

0.683***

(0.187)

0.401

(0.262)

F-value 7.24*** 10.63*** 5.50*** 3.77***

R2 0.171 0.245 0.123 0.080

Moran’s I p-value 0.375 0.380 0.000 0.004

Observations 289 289 289 289

Notes: *** p<0.01, ** p<0.05, * p<0.1. Robust standard errors in Model 5b, 6a and 6b.

In addition, higher unrelated variety in industries is found to be negative for unadjusted employment

growth in manufacturing. Since unrelated variety in industries measures inverse industrial

specialization this implies that positive localization economies is found for employment growth and

not productivity growth.

Regarding related variety among employees, the positive productivity effect from related variety in

education is robust for the manufacturing sector. The magnitude of this effect is particularly strong for

the industry-adjusted growth. In addition, this variable is positively enhancing adjusted employment

growth in the manufacturing sector. Hence, related variety in education is an important variable in

general and for the manufacturing sector in particular. For the private sector as a whole no effect was

found from related variety in occupation. However, the results regarding the service sector show that

related variety in occupation has a significant positive effect on both unadjusted and adjusted

productivity growth. This may be interpreted as that cognitive proximity among employees is

important for productivity growth in both sectors. For manufacturing, relatedness in terms of

educational background still matters while for services it is relatedness in current occupation. Related

variety in occupation is also positively enhancing employment growth in manufacturing, implying that

cognitive proximity is important for the manufacturing sector in general terms.

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A somewhat contradicting result is that unrelated variety in education is productivity enhancing for

services. The magnitude of the effect is robust across unadjusted and adjusted growth rates. This

shows a difference from the manufacturing sector in that the service sector benefits from broad

diversity among employees as well. On the other hand, unrelated variety in occupation has a negative

impact on unadjusted employment growth in the service sector, and related variety in education has a

positive impact when controlling for spatial autocorrelation (see Appendix 5). Hence, it is not possible

to draw general conclusions for the service sector, as above for the manufacturing sector. This could

be due to that the service sector is comprised of a more diverse set of industries than the

manufacturing sector.

Regarding the control variables, competition has a positive impact on unadjusted employment growth,

both for the overall private sector and for manufacturing and services separately. In addition, we find a

weakly significant positive competition effect for unadjusted productivity growth in the manufacturing

sector. Regarding adjusted employment growth, the competition effect is negative for the private

economy as a whole but insignificant for manufacturing and services separately. Moreover, we find

that population density is positive for adjusted growth in both productivity and employment.

5. CONCLUSIONS

In this paper we tested the role that related variety in education and occupation play in regional

growth. While most analyses of regional variety put firms and sectors in center stage, we argue that

knowledge spillovers occur primarily between individuals. Relatedness between individuals in terms

of education and occupation may be at least as important as industries in stimulating knowledge

spillovers and regional growth. To test the empirical relevance of these arguments we added measures

of education and occupational variety (related and unrelated) to the basic empirical model of Frenken

et al. (2007) and estimated the relative importance of the three dimensions of related variety. As in

previous findings, we found that related variety in industries has a positive effect on growth in

employment but a negative effect on growth in productivity.

However, we also show that related variety in education is positively associated with productivity

growth in the private sector in general and the manufacturing sector in particular, while related variety

in occupation is positively related to productivity growth in the service sector. These results broadly

support that relatedness in terms of the education and occupation of employees are conducive for

knowledge spillovers that stimulate the productivity growth of a region. The potential of productive

interactions between employees in a region is greater when there is related variety in their knowledge

base.

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The findings also bear on policy in the sense that they illustrate the multi-dimensional nature of the

notion of relatedness. The recent policy concept of smart specialization suggest for instance that

regions should focus on locally strong areas, and develop into areas that are related to these. The way

in which relatedness is conceptualized clearly plays a crucial role in such efforts. Relatedness in

industries and relatedness in employee education and skills do not necessarily go hand-in-hand,

especially in view of that many regions are functionally specialized such that the functions within a

given industry differ widely across regions.

While the results in this paper is consistent with the idea that knowledge spillovers works better in

contexts when related variety is high, it should be stated that the analysis does not inform about the

mechanisms. For example, we do not know whether the estimated relationships reflect pure

knowledge spillovers, better local matching efficiency, or embodied knowledge flows mediated by

local inter-firm labor mobility. Related variety in either industries, education or occupation could

stimulate either of these mechanism. Further work may focus on untangling the mechanism behind

the empirical regularity of a strong association between related variety and growth.

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APPENDIX 1

Table A1. Educational codes.

Educational code

(Sun2000Inr)

Education focus

01 General education

08 Reading and writing for adults

09 Personal development

14 Pedagogics and teaching

21 Arts and media

22 The humanities

31 Social and behavioral science

32 Journalism and information

34 Business

38 Law and legal science

42 Biology and environmental science

44 Physics, chemistry and geoscience

46 Mathematics and natural science

48 Computer science

52 Engineering: Technical, mechanical, chemical and electronics

54 Engineering: Manufacturing

58 Engineering: Construction

62 Agriculture

64 Animal healthcare

72 Healthcare

76 Social work

81 Personal services

84 Transport services

85 Environmental care

86 Security

99 Unknown

Table A2. Occupational codes.

ISCO/SSYK

code

Occupation

0 Militaries

1 Managers, legislators and senior officials

21 & 31 Physical, mathematical and engineering science professionals and associate

professionals

22 & 32 Life science and health professionals and associate professionals

23 & 33 Teaching professionals and associate professionals

24 & 34 Other professionals and associate professionals

4 Office and customer services clerks

5 Salespersons, demonstrators, personal and protective services workers

6 Market-oriented skilled agricultural and fishery workers

7 Extraction, building, metal, machinery, handicraft and related trades workers

81 Stationary-plant, machine, mobile-plant and related operators

91 Sales and services elementary occupations, agricultural, mining, transport

and related laborers

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APPENDIX 2

RV Industry RV Education RV Occupation

UV Industry UV Education UV Occupation

Figure A1. Quantile maps of related and unrelated variety, the private sector (darker color implies

greater variety).

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RV Industry RV Education RV Occupation

UV Industry UV Education UV Occupation

Figure A2. Quantile maps of related and unrelated variety, the manufacturing sector (darker color

implies greater variety).

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RV Industry RV Education RV Occupation

UV Industry UV Education UV Occupation

Figure A3. Quantile maps of related and unrelated variety, the service sector (darker color implies

greater variety).

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Figure A4. Quantile map of the population density in Sweden 2002 (darker color implies greater

population density).

Stockholm Gothenburg

Malmö

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APPENDIX 3 Table A3. Descriptive statistics for the private sector.

Mean Std. dev. Min Max

Productivity growth 1.26 .178 .824 2.28

Productivity growth adjusted 1.14 .412 .519 5.70

Employment growth 1.06 .091 .726 1.45

Employment growth adjusted 1.03 .165 .539 1.82

RV Industry 1.33 .344 .455 2.16

UV Industry 2.68 .234 1.69 3.12

RV Education 1.52 .138 1.18 1.86

UV Education 2.14 .177 1.69 2.88

RV Occupation 1.55 .129 .885 1.82

UV Occupation 1.97 .118 1.58 2.25

Competition .142 .050 .051 .303

Pop. density 125 420 .257 4,040

Capital-labor growth 1.18 .422 .353 4.57

Productivity 02 521 107 250 1,070

Employment 02 8,430 24,500 285 353,000

Table A4. Descriptive statistics for the manufacturing sector.

Mean Std. dev. Min Max

Productivity growth 1.30 .240 .711 2.84

Productivity growth adjusted 1.01 .388 .432 4.90

Employment growth 1.03 .128 .656 1.71

Employment growth adjusted .923 .266 .357 2.66

RV Industry .535 .151 .102 1.13

UV Industry 1.32 .260 .420 2.18

RV Education 1.43 .157 .948 1.83

UV Education 2.10 .177 1.69 2.88

RV Occupation 1.53 .190 .573 1.86

UV Occupation 1.69 .144 1.20 2.00

Competition .102 .057 .018 .391

Capital-labor growth 1.25 .576 .299 4.59

Productivity 02 545 153 196 1,350

Employment 02 3,480 6,120 101 67,700

Table A5. Descriptive statistics for the service sector.

Mean Std. dev. Min Max

Productivity growth 1.22 .214 .861 2.86

Productivity growth adjusted 1.25 .696 .566 9.97

Employment growth 1.10 .117 .737 1.56

Employment growth adjusted 1.10 .201 .667 2.52

RV Industry .791 .331 .241 1.78

UV Industry 1.37 .292 .627 2.09

RV Education 1.45 .175 1.04 1.85

UV Education 2.12 .187 1.67 2.88

RV Occupation 1.23 .137 .855 1.54

UV Occupation 2.04 .071 1.61 2.29

Competition .200 .051 .050 .317

Capital-labor growth 1.15 .577 .257 6.83

Productivity 02 475 63.4 333 823

Employment 02 4,950 18,900 181 285,000

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APPENDIX 4 Table A6. Correlation matrix for independent variables (in logarithmic form), the private sector.

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

1. RV Industry 1

2. UV Industry .620 1

3. RV Education .488 .261 1

4. UV Education .571 .331 .664 1

5. RV Occupation .376 .574 .120 .002 1

6. UV Occupation .693 .577 .569 .668 .150 1

7. Competition .256 .229 -.276 .158 -.162 .371 1

8. Pop. density .384 .062 .449 .425 .007 .273 -.167 1

9. Capital-labor gr. -.108 -.105 -.139 -.119 -.055 -.113 .020 -.097 1

10. Productivity 02 .004 -.120 .414 .156 .038 .037 -.441 .389 -.248 1

11. Employment 02 .582 .348 .693 .471 .372 .326 -.512 .614 -.118 .412 1

Table A7. Correlation matrix for independent variables (in logarithmic form), the manufacturing

sector.

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

1. RV Industry 1

2. UV Industry .525 1

3. RV Education -.073 -.067 1

4. UV Education -.240 -.474 .606 1

5. RV Occupation .407 .250 .272 .248 1

6. UV Occupation .015 -.141 .487 .602 .379 1

7. Competition .069 -.374 -.478 .099 .048 .159 1

8. Pop. density -.167 -.307 .464 .511 .108 .345 -.105 1

9. Capital-labor gr. -.032 -.044 -.055 -.093 -.082 -.157 -.023 -.086 1

10. Productivity 02 -.097 -.010 .452 .217 .022 .169 -.391 .315 -.183 1

11. Employment 02 .123 .099 .794 .467 .372 .332 -.572 .552 -.023 .409 1

Table A8. Correlation matrix for independent variables (in logarithmic form), the service sector.

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.

1. RV Industry 1

2. UV Industry .897 1

3. RV Education .750 .636 1

4. UV Education .786 .791 .725 1

5. RV Occupation .568 .409 .650 .466 1

6. UV Occupation .230 .173 .200 .189 .366 1

7. Competition -.403 -.358 -.638 -.436 -.523 .143 1

8. Pop. density .456 .267 .456 .433 .496 .099 -.323 1

9. Capital-labor gr. -.053 -.033 -.183 -.063 -.141 -.086 .095 -.042 1

10. Productivity 02 .346 .205 .498 .375 .469 .092 -.476 .553 -.253 1

11. Employment 02 .752 .586 .817 .655 .745 .149 -.743 .610 -.138 .564 1

Page 29: Which Types of Relatedness Matter in Regional Growth ... · Which Types of Relatedness Matter in Regional Growth? - industry, occupation and education Sofia WixeƟ and Martin AnderssonØ

29

APPENDIX 5

In the spatial error model the error term of equation 5, εr, is replaced by ur where:

in which Wr is a spatial weight matrix taking the travel time distances between municipalities into

account. λ is the spatial error coefficient, which is equal to zero when there is no spatial correlation in

the error terms. The spatial lag model includes a spatially lagged dependent variable as an additional

explanatory variable. Hence, is introduced on the right hand side of Equation 5. ρ is the

spatial coefficient, which is zero when there is no spatial dependence, implying that the municipal

growth is independent of the growth in neighboring municipalities. (Anselin 2003) Model selection is

based on maximum likelihood values, which implies that in each case the model with the largest

maximum likelihood value is presented.

Table A9. Estimated coefficients for the spatial models regarding productivity growth and

employment growth. Standard errors in brackets.

Variables 2b’

Private

Employment

ML(lag)

Adjusted

3b’

Manufacturing

Productivity

ML(error)

Adjusted

4a’

Services

Productivity

ML(error)

6a’

Services

Employment

ML(error)

6b’

Services

Employment

ML (lag)

Adjusted

RV Industry 0.157***

(0.050)

0.081

(0.058)

-0.133***

(0.030)

0.074***

(0.024)

0.043

(0.040)

UV Industry 0.049

(0.139)

0.159

(0.101)

RV Education 0.050

(0.169)

1.35***

(0.251)

0.000

(0.123)

0.192**

(0.098)

0.194

(0.153)

UV Education -0.298*

(0.163)

0.260

(0.309)

0.726***

(0.147)

-0.246**

(0.123)

-0.170

(0.191)

RV Occupation 0.005

(0.129)

0.068

(0.123)

0.247**

(0.099)

-0.029

(0.081)

0.071

(0.131)

UV Occupation 0.306

(0.255)

0.051

(0.223)

-0.410*

(0.242)

-0.510***

(0.196)

-0.370

(0.322)

Competition -0.094***

(0.036)

0.048

(0.047)

-0.045

(0.038)

0.093***

(0.030)

0.016

(0.050)

Population density 0.016**

(0.007)

0.028**

(0.014)

0.010

(0.007)

0.011*

(0.006)

0.010

(0.007)

Capital labor growth -0.014

(0.036)

0.063***

(0.019)

Productivity 2002 -0.161**

(0.067)

-0.503***

(0.076)

Constant -0.326*

(0.194)

0.297

(0.437)

2.83***

(0.478)

0.713***

(0.169)

0.366

(0.280)

Spatial coefficient 0.333**

(0.145)

0.365**

(0.154)

0.260

(0.177)

0.478***

(0.143)

0.338**

(0.156)

R2 0.236 0.346 0.255 0.128 0.088

Observations 289 289 289 289 289

Notes: *** p<0.01, ** p<0.05, * p<0.1. R2 is a psudo-R

2 corresponding to the variance ratio.